This invention relates generally to evaporator systems, and more particularly to small compact systems, such as would be used in association with automotive air conditioners.
A typical example of this type of product in the prior art is seen in U.S. Pat. No. 4,244,194, issued to Hermann Haesters for Evaporator Particularly for Air Conditioning Devices, on Jan. 13, 1981. In this patent, a plurality of U-shaped tubes are attached to a distributor part by having their open ends bonded by a curable plastic in annular grooves in the distributor part. The applicant's use, in contrast, of expandable plastic, is between his exposed, but closed pipe ends and loops that extend beyond the horizontal fins at each end of his assembly for the purpose of preserving cooling capacity and preventing sweating, neither of which purposes would be accomplished by the substantial exposure of the U-shaped evaporator pipes 3 at the top of the patentee's FIG. 1.
Other examples of prior art evaporators are seen in the following U.S. patents:
U.S. Pat. No. 3,422,884 to P. S. Otten, for Condenser Tube Bundles, issued Jan. 21, 1969, discloses a technique for assembling and supporting condenser tube bundles wherein a foam plastic surrounds the ends of the condenser tubes and between spaced header plates and is used to hold the tubes in place without welding.
U.S. Pat. No. 3,633,660 to F. M. Young, for Plastic Bonding of Heat Exchanger Core Units to Header Plate, issued Jan. 11, 1972, shows the use of a plastic bonding substance at the upper ends of a plurality of heat exchanger tubes for the purpose of bonding the tubes to a dished header plate without the use of solder to reduce breakage due to vibration.
The U.S. Pat. No. 4,036,288 to R. Neveux, for Radiator for Air Conditioning System of an Automobile, issued July 19, 1977, uses a band of foam material to surround a stack of cooling fins supporting evaporator tubes in a manner to contribute to the lightness of the mounting of the radiator into an installational conduit.
U.S. Pat. No. 4,114,397 to R. Takehashi, et al, for Evaporator, issued Sept. 19, 1978, employs a tube plate to which upper ends of a plurality of U-tubes are fixed and wherein the lower ends of all tubes are U-shaped in a hairpin configuration. This patent does not teach the use of an expandable plastic foam material to both insulate the U-shaped ends and prevent condensation of water on their external surfaces.
The patent ot J-F Bouvot, U.S. Pat. No. 4,328,859 for Mounting for Heat Exchanger in Housing of Auto Air Conditioner, issued May 11, 1982, discloses a mounting technique that uses a belt of compressible foam material to accommodate varying tolerances in mounting dimensions and to minimize vibration effects after installation.
Also part of the prior art are the examples shown in applicant's FIGS. 1-2b in the drawing. FIG. 1 represents an example of the type of automotive air conditioner evaporator unit that is available for purchase by automotive repair shops and mechanics for installation in automobiles in the "after market", i.e., replacement parts in new or used automobiles that are no longer under factory warranty. FIG. 2 in contrast thereto, represents an example of the type of automotive air conditioner evaporator unit that is installed on new cars at the factory, and this type of product is known in the trade as O. E. M., which is the acronym for "Original Equipment Manufacture".
FIG. 1 shows the evaporator unit "A" installed within an automotive air conditioning cowling "C", but since the dimensions of A do not provide a precise fit, the open areas are filled with a packing material "P". In operation, the refrigerant "R" enters into fitting f.sub.1 and travels through four reduced diameter (1/8" vs. 3/8" in rest of cycle) tubes to enter each of four in-line circulation paths as seen more clearly in FIG. 1a. So in this unit, the refrigerant entering the evaporator unit from each input tube i travels the full longitudinal length of the evaporator with many U-turns before exiting through output manifold m and outlet fitting f.sub.2. The cooling fins F.sub.1 of this unit are oriented vertically because it was thought that condensation on the fins should flow downward to permit drainage from the bottom of cowling C.
FIG. 2 shows the evaporator unit "B" installed in the same cowling C as unit "A" was. This unit has the same air flow path as A, i.e., into the paper as viewing each drawing, but instead of long vertical fins, it has a greater number of small accordian like fins F.sub.2, that extend horizontally between vertical extending tube sections T that provide for a plurality of very small diameter (1/8") formed tubes t.sub.1 that open into the large cavity of horizontal end chambers E at the top and bottom of unit B. In this unit there is no precise circulatory path for refrigerant entering inlet fitting f.sub.3 and exiting through outlet fitting f.sub.4, since all of the refrigerant entering passes into the large cavity end chamber E at the bottom of unit B and travels upward (while expanding) through the large plurality of vertical tubes t.sub.1 and exits into the top end chamber E and out through outlet fitting f.sub.4. The large expansion chambers E at top and bottom of the Evaporator B are made up of a plurality of vertical sections with three large openings O in each section, so that the refrigerant flows from the five very small tubes t.sub.1 into the very large open areas afforded by the chamber E. These large chambers E permit very rapid expansion of the refrigerant and this contributes to freeze up in the very small tubes t.sub.1. Also there is substantial condensation on the outside of the top and bottom end chambers, which is undesirable and represents loss of cooling capacity and wasted energy. Further, the exterior of the top and bottom chambers E comprises very sharp edges which are difficult and dangerous to handle at installation of the evaporator into its cowling.
The applicant's product, as will be described in more detail hereafter, in contrast, comprises a specified number of well defined refrigerant travel paths through his unit 1, and his top and bottom areas are covered to prevent sharp edges, and to provide an attractive compact plastic housing that is contoured for strength and insulation holding purposes with no exposed sharp edges, either on his fins (as in the case with unit A of FIG. 1) or with the top or bottom exterior exposed (as in the case of unit B of FIG. 2). Further, his top and bottom exterior covers provide a receptability area to hold an expandable foamlike insulation which has the multiple purpose of insulating the normally exposed U-tubes in the refrigerant travel cycles, and of preventing "sweating" or moisture condensation at those locations. In summary, the applicant's evaporator is compact, attractive, less dangerous to handle, and more efficient in operation when compared to the prior art units.